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hackercup / 2022 /round3 /zero_crossings_ch1.java
wjomlex's picture
2022 Problems
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import java.io.PrintWriter;
import java.text.DecimalFormat;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Scanner;
import java.util.TreeSet;
public class ZeroCrossingsCh1 {
static double globalX = 0;
static void solve(Scanner fs, PrintWriter out, int tt) {
int nHulls = fs.nextInt();
Hull[] hulls = new Hull[nHulls + 1];
for (int i = 0; i < nHulls; i++) {
hulls[i] = new Hull(fs);
}
hulls[nHulls] = new Hull();
for (int i = 0; i <= nHulls; i++) {
hulls[i].id = i;
}
ArrayList < Event > events = new ArrayList<>();
for (Hull h: hulls) {
events.addAll(h.getEvents());
}
int nQ = fs.nextInt();
Query[] queries = new Query[nQ];
for (int qq = 0; qq < nQ; qq++) {
queries[qq] = new Query(fs);
events.addAll(queries[qq].getEvents());
}
Collections.sort(events);
TreeSet<Seg> set = new TreeSet<>((a, b) -> {
double ay = a.evalAt(globalX),
by = b.evalAt(globalX);
return Double.compare(ay, by);
});
for (Event e: events) {
globalX = e.x;
if (e.qp != null) {
Vec position = e.qp.position;
Seg hSeg = new Seg(position, position.add(new Vec(1, 0)));
Seg higher = set.higher(hSeg);
e.qp.node = parent(higher, hulls[nHulls]);
} else {
if (e.isEval) {
Seg higher = set.higher(e.s);
e.s.hull.parent = parent(higher, hulls[nHulls]);
e.s.hull.parent.children.add(e.s.hull);
} else if (e.isStart) {
set.add(e.s);
} else {
set.remove(e.s);
}
}
}
hulls[nHulls].calcSubtreeHash();
hulls[nHulls].calcAllHash(new HarmeyerHash(), new HarmeyerHash());
int ans = 0;
for (Query qq: queries) {
Hull node1 = qq.qp1.node, node2 = qq.qp2.node;
boolean possible = node1.allHash.equals(node2.allHash);
if (possible) ans++;
}
out.println("Case #" + tt + ": " + ans);
}
static Hull parent(Seg higher, Hull rootHull) {
if (higher == null) {
return rootHull;
} else if (higher.isUpper) {
//father
return higher.hull;
} else {
//brother
return higher.hull.parent;
}
}
// at a particular x:
// query points (-0.3)
// removals (-0.1)
// additions(+0.1)
// evals(+0.3)
static class Event implements Comparable < Event > {
double x,
y;
boolean isStart;
boolean isEval;
Seg s;
QueryPoint qp;
public Event(boolean isStart, Seg s, QueryPoint qp, boolean isEval) {
this.isStart = isStart;
this.isEval = isEval;
this.s = s;
this.qp = qp;
if (this.s == null) {
x = qp.position.x - 0.3;
} else {
if (isStart) {
x = s.from.x + 0.1;
} else if (isEval) {
x = s.from.x + 0.3;
y = s.from.y;
} else {
x = s.to.x - 0.1;
}
}
}
public int compareTo(Event o) {
if (x != o.x) return Double.compare(x, o.x);
//process higher y first, since we look upwards
return Double.compare(o.y, y);
}
}
static class Hull implements Comparable < Hull > {
int nPoints;
Vec[] points;
Vec[] upperHull,
lowerHull;
Seg[] upperHullSegs,
lowerHullSegs;
int id;
Hull parent;
ArrayList < Hull > children = new ArrayList<>();
HarmeyerHash subtreeHash;
HarmeyerHash allHash;
//root hull
public Hull() {}
public Hull(Scanner fs) {
nPoints = fs.nextInt();
points = new Vec[nPoints];
for (int i = 0; i < nPoints; i++) {
points[i] = new Vec(fs.nextInt(), fs.nextInt());
}
if (area() < 0) {
Vec[] newPoints = new Vec[nPoints];
for (int i = 0; i < nPoints; i++) newPoints[i] = points[nPoints - 1 - i];
points = newPoints;
}
Vec[] sorted = points.clone();
Arrays.sort(sorted, (a, b) -> {
if (a.x != b.x) return Double.compare(a.x, b.x);
return Double.compare(a.y, b.y);
});
int leftInd = 0, rightInd = 0;
for (int i = 0; i < nPoints; i++)
if (points[i] == sorted[0]) leftInd = i;
for (int i = 0; i < nPoints; i++)
if (points[i] == sorted[nPoints - 1]) rightInd = i;
if (rightInd < leftInd) rightInd += nPoints;
lowerHull = new Vec[rightInd - leftInd + 1];
for (int i = leftInd; i <= rightInd; i++) lowerHull[i - leftInd] = points[i % nPoints];
while (leftInd < rightInd) leftInd += nPoints;
upperHull = new Vec[leftInd - rightInd + 1];
for (int i = rightInd; i <= leftInd; i++) upperHull[leftInd - i] = points[i % nPoints];
upperHullSegs = new Seg[upperHull.length - 1];
for (int i = 0; i + 1 < upperHull.length; i++) upperHullSegs[i] = new Seg(upperHull[i], upperHull[i + 1]);
lowerHullSegs = new Seg[lowerHull.length - 1];
for (int i = 0; i + 1 < lowerHull.length; i++) lowerHullSegs[i] = new Seg(lowerHull[i], lowerHull[i + 1]);
for (Seg s: upperHullSegs) {
s.isUpper = true;
s.hull = this;
}
for (Seg s: lowerHullSegs) {
s.isUpper = false;
s.hull = this;
}
}
double area() {
double area = 0;
for (int i = 0; i < points.length; i++) {
area += points[i].cross(points[(i + 1) % nPoints]);
}
return area / 2;
}
// Add events for all lines which aren't vertical.
ArrayList < Event > getEvents() {
if (nPoints == 0) {
// Root query.
return new ArrayList<>();
}
ArrayList < Event > res = new ArrayList<>();
Seg firstUpper = null;
for (Seg s: upperHullSegs) {
if (s.isVertical()) continue;
if (firstUpper == null) firstUpper = s;
res.add(new Event(true, s, null, false));
res.add(new Event(false, s, null, false));
}
for (Seg s: lowerHullSegs) {
if (s.isVertical()) continue;
res.add(new Event(true, s, null, false));
res.add(new Event(false, s, null, false));
}
res.add(new Event(false, firstUpper, null, true));
return res;
}
void calcSubtreeHash() {
for (Hull hh: children) {
hh.calcSubtreeHash();
}
Collections.sort(children);
HarmeyerHash me = new HarmeyerHash();
me.add('(');
for (Hull hh: children) {
me.append(hh.subtreeHash);
}
me.add(')');
this.subtreeHash = me;
}
void calcAllHash(HarmeyerHash prefix, HarmeyerHash suffix) {
prefix = prefix.clone();
suffix = suffix.clone();
allHash = new HarmeyerHash();
allHash.add('s');
allHash.append(prefix);
allHash.add('S');
allHash.append(subtreeHash);
allHash.add('e');
allHash.append(suffix);
allHash.add('E');
// Now we need to calculate this for our kids
prefix.add('('); {
HarmeyerHash temp = new HarmeyerHash();
temp.add(')');
temp.append(suffix);
suffix = temp;
}
HarmeyerHash[] subtreesCS = new HarmeyerHash[children.size() + 1];
subtreesCS[0] = new HarmeyerHash();
for (int i = 1; i <= children.size(); i++) {
subtreesCS[i] = subtreesCS[i - 1].clone();
subtreesCS[i].append(children.get(i - 1).subtreeHash);
}
for (int at = 0; at < children.size(); at++) {
int countIdentical = 1;
while (at + countIdentical < children.size() &&
children.get(at + countIdentical).subtreeHash.equals(
children.get(at).subtreeHash)) {
countIdentical++;
}
HarmeyerHash beforeGroup = subtreesCS[at];
HarmeyerHash afterMe = subtreesCS[children.size()].clone();
afterMe.subHash(subtreesCS[at + 1]);
HarmeyerHash groupPrefix = prefix.clone();
groupPrefix.append(beforeGroup);
HarmeyerHash groupSuffix = afterMe.clone();
groupSuffix.append(suffix);
for (int inGroup = 0; inGroup < countIdentical; inGroup++) {
children.get(at + inGroup).calcAllHash(groupPrefix, groupSuffix);
}
at += countIdentical - 1;
}
}
public int compareTo(Hull o) {
return subtreeHash.compareTo(o.subtreeHash);
}
}
static class QueryPoint {
Query q;
Vec position;
Hull node;
public QueryPoint(Query q, Vec p) {
this.q = q;
this.position = p;
}
Event getEvent() {
return new Event(false, null, this, false);
}
}
static class Query {
QueryPoint qp1, qp2;
public Query(Scanner fs) {
Vec p1 = new Vec(fs.nextInt(), fs.nextInt());
Vec p2 = new Vec(fs.nextInt(), fs.nextInt());
qp1 = new QueryPoint(this, p1);
qp2 = new QueryPoint(this, p2);
}
ArrayList < Event > getEvents() {
ArrayList < Event > res = new ArrayList<>();
res.add(qp1.getEvent());
res.add(qp2.getEvent());
return res;
}
}
static class VecL implements Comparable < VecL > {
long x, y;
public VecL(long x, long y) {
this.x = x;
this.y = y;
}
public VecL add(VecL o) {
return new VecL(x + o.x, y + o.y);
}
public VecL sub(VecL o) {
return new VecL(x - o.x, y - o.y);
}
public VecL scale(long s) {
return new VecL(x * s, y * s);
}
public long dot(VecL o) {
return x * o.x + y * o.y;
}
public long cross(VecL o) {
return x * o.y - y * o.x;
}
public long mag2() {
return dot(this);
}
public VecL rot90() {
return new VecL(-y, x);
}
public VecL rot270() {
return new VecL(y, -x);
}
public String toString() {
return "(" + x + ", " + y + ")";
}
public int hashCode() {
return Long.hashCode(x << 13 ^ (y * 57));
}
public boolean equals(Object oo) {
VecL o = (VecL) oo;
return x == o.x && y == o.y;
}
public int compareTo(VecL o) {
if (x != o.x) return Long.compare(x, o.x);
return Long.compare(y, o.y);
}
// origin->q1, axes-> quadrant in ccw direction
public int quadrant() {
if (x == 0 || y == 0) {
if (y == 0) {
return x >= 0 ? 1 : 3;
}
return y >= 0 ? 2 : 4;
}
if (x > 0) {
return y > 0 ? 1 : 4;
}
return y > 0 ? 2 : 3;
}
public int radialCompare(VecL o) {
if (quadrant() == o.quadrant()) {
return -Long.signum(cross(o));
}
return Integer.compare(quadrant(), o.quadrant());
}
}
static class Vec {
static final double EPS = 1e-6;
double x, y;
public Vec(double x, double y) {
this.x = x;
this.y = y;
}
public Vec add(Vec o) {
return new Vec(x + o.x, y + o.y);
}
public Vec sub(Vec o) {
return new Vec(x - o.x, y - o.y);
}
public Vec scale(double s) {
return new Vec(x * s, y * s);
}
public double dot(Vec o) {
return x * o.x + y * o.y;
}
public double cross(Vec o) {
return x * o.y - y * o.x;
}
public double mag2() {
return dot(this);
}
public double mag() {
return Math.sqrt(mag2());
}
public Vec unit() {
return scale(1 / mag());
}
public Vec rot90() {
return new Vec(-y, x);
}
public Vec rot270() {
return new Vec(y, -x);
}
public Vec rotate(double theta) {
double PI = Math.PI;
double newX = x * Math.cos(theta) + y * Math.cos(PI / 2 + theta);
double newY = x * Math.sin(theta) + y * Math.sin(PI / 2 + theta);
return new Vec(newX, newY);
}
// Angle between 0 and 2PI
public double angle() {
return (Math.atan2(y, x) + 2 * Math.PI) % (2 * Math.PI);
}
public String toString() {
DecimalFormat df = new DecimalFormat("#.##");
return "(" + df.format(x) + ", " + df.format(y) + ")";
}
static boolean eq(double a, double b) {
return Math.abs(a - b) < EPS;
}
static boolean leq(double a, double b) {
return a - EPS < b;
}
static boolean geq(double a, double b) {
return a + EPS > b;
}
public boolean equals(Object oo) {
Vec o = (Vec) oo;
return eq(x, o.x) && eq(y, o.y);
}
}
static class Seg {
Vec from, to, dir;
Hull hull;
boolean isUpper;
double m, b;
public Seg(Vec from, Vec to) {
this.from = from;
this.to = to;
dir = to.sub(from);
if (!isVertical()) {
m = dir.y / dir.x;
b = from.y - m * from.x;
}
}
boolean isVertical() {
return Math.abs(dir.x) < 0.5;
}
double evalAt(double x) {
return m * x + b;
}
//line-line intersection
public Vec lineIntersect(Seg o) {
double det = o.dir.x * dir.y - dir.x * o.dir.y;
if (Vec.eq(det, 0)) {
return null;
}
double dist = (o.dir.x * (o.from.y - from.y) -
o.dir.y * (o.from.x - from.x)) / det;
return from.add(dir.scale(dist));
}
public boolean containsPoint(Vec o) {
double distFromLine = dir.unit().cross(o.sub(from));
if (!Vec.eq(distFromLine, 0)) {
return false;
}
return Vec.eq(dir.mag(), from.sub(o).mag() + to.sub(o).mag());
}
// seg-seg intersection
public Vec segIntersection(Seg o) {
Vec intersect = lineIntersect(o);
if (intersect == null) {
return null;
}
return containsPoint(intersect) && o.containsPoint(intersect) ? intersect
: null;
}
// returns 1 if above, 0 if on, -1 if below
public int side(Vec o) {
Vec oDir = o.sub(from);
double distFromLine = dir.unit().cross(oDir);
if (Vec.eq(distFromLine, 0)) {
return 0;
}
return (int)Math.signum(distFromLine);
}
public boolean intersects(Seg o) {
return side(o.from) != side(o.to) && o.side(from) != o.side(to);
}
public Vec getClosestTo(Vec o) {
double percentThere = o.sub(from).dot(dir) / dir.mag2();
return from.add(dir.scale(Math.max(0, Math.min(1, percentThere))));
}
public Vec projectToLine(Vec o) {
return dir.scale(o.sub(from).dot(dir) / dir.mag2()).add(from);
}
// toContain must be a point with positive x and y coordinates.
// this method returns the shortest line segment from the x-axis to the
// point to the y axis
public static Seg getShortestSegFromAxesContainingQ1Point(Vec toContain) {
double slope = -Math.pow(toContain.y / toContain.x, 1.0 / 3);
double b = toContain.y - toContain.x * slope;
double xInt = -b / slope;
return new Seg(new Vec(0, b), new Vec(xInt, 0));
}
public String toString() {
return from + " -> " + to;
}
}
public static void main(String[] args) throws InterruptedException {
Thread t = new Thread(null, null, "", 1 << 29) {
public void run() {
A(null);
}
};
t.start();
t.join();
}
public static void A(String[] args) {
Scanner fs = new Scanner(System.in);
PrintWriter out = new PrintWriter(System.out);
long time = System.currentTimeMillis();
int T = fs.nextInt();
for (int tt = 0; tt < T; tt++) {
solve(fs, out, tt + 1);
}
fs.close();
out.close();
}
// Cannot use 0 as a character in the strings
static class HarmeyerHash implements Comparable < HarmeyerHash > {
static final long m1 = 8675309, m2 = 1_000_000_007, m3 = 1_000_000_009;
long v1 = 0, v2 = 0, v3;
int l = 0;
static final long s1 = 257, s2 = 619, s3 = 10007;
static long[] s1Pow, s2Pow, s3Pow;
static boolean precomped = false;
void add(char o) {
v1 = (v1 * s1 + o) % m1;
v2 = (v2 * s2 + o) % m2;
v3 = (v3 * s3 + o) % m3;
l++;
}
void subHash(HarmeyerHash smallerPrefix) {
HarmeyerHash old = this;
HarmeyerHash toSub = smallerPrefix;
int diff = this.l - smallerPrefix.l;
old.v1 = (old.v1 - (toSub.v1 * s1Pow[diff]) % m1 + m1) % m1;
old.v2 = (old.v2 - (toSub.v2 * s2Pow[diff]) % m2 + m2) % m2;
old.v3 = (old.v3 - (toSub.v3 * s3Pow[diff]) % m3 + m3) % m3;
l = diff;
}
public int compareTo(HarmeyerHash o) {
if (v1 != o.v1) {
return Long.compare(v1, o.v1);
}
if (v2 != o.v2) {
return Long.compare(v2, o.v2);
}
return Long.compare(v3, o.v3);
}
public boolean equals(Object o) {
return compareTo((HarmeyerHash) o) == 0;
}
public int hashCode() {
return (int)v1;
}
public HarmeyerHash clone() {
HarmeyerHash toReturn = new HarmeyerHash();
toReturn.v1 = v1;
toReturn.v2 = v2;
toReturn.v3 = v3;
toReturn.l = l;
return toReturn;
}
static void precomp() {
if (precomped) {
return;
}
precomped = true;
s1Pow = new long[10_000_000];
s2Pow = new long[10_000_000];
s3Pow = new long[10_000_000];
s1Pow[0] = s2Pow[0] = s3Pow[0] = 1;
for (int i = 1; i < s1Pow.length; i++) {
s1Pow[i] = (s1Pow[i - 1] * s1) % m1;
}
for (int i = 1; i < s2Pow.length; i++) {
s2Pow[i] = (s2Pow[i - 1] * s2) % m2;
}
for (int i = 1; i < s3Pow.length; i++) {
s3Pow[i] = (s3Pow[i - 1] * s3) % m3;
}
}
//need fastPow if o can be longer than 10^6
void append(HarmeyerHash o) {
precomp();
v1 = (v1 * s1Pow[o.l] + o.v1) % m1;
v2 = (v2 * s2Pow[o.l] + o.v2) % m2;
v3 = (v3 * s3Pow[o.l] + o.v3) % m3;
l += o.l;
}
public static HarmeyerHash[] getPrefixHashes(char[] word) {
precomp();
int n = word.length;
HarmeyerHash[] toReturn = new HarmeyerHash[n + 1];
toReturn[0] = new HarmeyerHash();
for (int i = 1; i <= n; i++) {
toReturn[i] = toReturn[i - 1].clone();
toReturn[i].add(word[i - 1]);
}
return toReturn;
}
//inclusive, exclusive
public static HarmeyerHash substringHash(HarmeyerHash[] prefixHashes, int from, int to) {
if (from == to) {
return new HarmeyerHash();
}
HarmeyerHash old = prefixHashes[to].clone(), toSub = prefixHashes[from];
int diff = to - from;
old.v1 = (old.v1 - (toSub.v1 * s1Pow[diff]) % m1 + m1) % m1;
old.v2 = (old.v2 - (toSub.v2 * s2Pow[diff]) % m2 + m2) % m2;
old.v3 = (old.v3 - (toSub.v3 * s3Pow[diff]) % m3 + m3) % m3;
old.l = to - from;
return old;
}
public String toString() {
return "[" + v1 + " " + v2 + " " + v3 + "]";
}
}
}